Human papilloma virus (HPV) and herpes simplex virus (HSV) infections account for significant morbidity among men who have sex with men (MSM). HPV is associated with oral, oropharyngeal, and anal cancers and a growing body of research suggests that racial disparities in HIV burden may be attributable, in part, to HSV infection. Building on our ongoing cohort study (The P18 cohort study; R01DA025537) of young MSM (YMSM), we will conduct an ancillary study to incorporate a comprehensive assessment of anal and oral HPV, HSV-1, and HSV-2 across time, all of which are highly prevalent infections among YMSM. Guided by syndemic theory, we will examine the sociodemographic, biological, behavioral, psychosocial/ structural determinants of these viral infections. Our work i informed by knowledge generated from the P18 cohort study thus far, which indicates inadequate sexual health care among cohort participants, ongoing incident HIV infections (7.2% to date), and a high level of infection with bacterial sexually transmitted infections (STIs) including chlamydia, gonorrhea, and syphilis. Moreover, there is evidence to suggest that YMSM have a very low likelihood of initiating HPV vaccination. Understanding the epidemiology of HPV and HSV infection as well as it associated correlates and predictors will provide a more comprehensive understanding of the multiple health burdens which compromise the overall health of YMSM. Further, understanding HPV and HSV infection among YMSM may shed light on the stark racial/ethnic disparities in HIV among YMSM. The proposed ancillary study is guided by the following aims: (1a) to detect cases of oral and anal HPV infection through site-specific PCR testing and clinically significant HPV subtypes (6, 11, 16, 18) through serotyping and to estimate HPV persistence and clearance rates; (1b) to identify uptake and completion of HPV vaccination; (2a) to determine the prevalence and incidence of HSV-1 and HSV-2; (2b) to prospectively estimate HIV risk among YMSM with and without HSV-1 and/or HSV-2 and to assess whether HSV infection explains racial/ethnic disparities in HIV risk; and (3) to determine the extent to which biological, behavioral and psychosocial/structural factors explain the likelihood of (a) oral/anal HPV infection, broadly and infection of HPV 6, 11, 16, and 18, specifically; (b) HPV vaccination uptake, (c) HSV-1 and HSV-2 infection, and (d) co-infections of HIV, HSV, and/or HPV. We will begin testing for HPV and HSV at our month 54 assessment and continue to test on a semi-annual basis for the duration of the study. Main analyses fall into two basic types: (1) cross-sectional analysis of correlates of HPV (overall and by subtype) and HSV-1 and HSV-2; and (2) prospective analysis of predictors of these viral STI outcomes. This study will provide much needed data on epidemiological trends of viral STIs among a racially/ethnically and socioeconomically diverse sample of YMSM as well as provide further insights on the potential salience of HPV, HSV-1, and HSV-2 on HIV transmission and acquisition.